A continuing goal in semiconductor processing is increased miniaturization while maintaining high performance. Modern semiconductor processes are still heavily reliant on lithography in fabricating integrated circuitry to achieve this goal.
Photolithography is a commonly-used method for patterning features during semiconductor processing. A radiation-sensitive material (i.e., photoresist) is formed over a substrate which is ultimately to be patterned, for example by etching or ion implanting. The photoresist is subsequently subjected to radiation which modifies the solubility of the exposed versus the non-exposed regions in a suitable developer solvent. Accordingly, the radiation is provided in a desired pattern so that some portions of the photoresist are exposed by the radiation while other portions of the photoresist are not exposed by the radiation. The photoresist is then subjected to developing conditions which selectively remove either the exposed or the non-exposed portions. Photoresists are designated to be either negative or positive. Exposed regions are selectively removed in a positive photoresist, while non-exposed regions are selectively removed in a negative photoresist.
The photoresist remaining after development defines a patterned mask on the substrate. The pattern of such mask can be subsequently transferred to the underlying material using appropriate etching and/or implanting techniques to form patterned features in material beneath the mask.
A problem which motivated embodiments of the invention disclosed herein pertains to water marks that remain on the positive photoresist surface after develop patterning. During develop or thereafter, the photoresist may be exposed to water, which can leave water marks on the outer surface of the photoresist. Such are commonly crystalline or other residual material which essentially deposits as a thin layer over the top of the photoresist in a blotchy manner. Some of these water marks actually extend over and into openings within the developed photoresist. Such can, of course, adversely affect subsequent processing of the substrate using the photoresist as a mask. Regardless, the patterned photoresist typically undergoes a post-development inspection or analysis prior to subsequent substrate processing using the mask to determine quality of the patterning of the photoresist mask. The water marks remaining over the substrate can adversely impact this inspection and analysis.
While embodiments of the invention were motivated in addressing the above-identified issues, it is no way so limited. Embodiments disclosed herein are only limited by the accompanying claims as literally worded, without interpretive or other limiting reference to the specification, and in accordance with the doctrine of equivalence.